Side impact protection

[Brands]

What is the general consensus on the side impact proctection? Kevlar in the body or alluminium panels? I'm guessing the Kevlar route is the lightest and easiest. Forming ally panels around a zetec frame looks tricky. What do the Stohr and Phoenix use?
Thanks

[RobLav]

Kevlar in the body must be easier. I hand formed .063 alloy around my RF96 Hayabusa conversion, and it was a pain. Ended up having to make a few pieces each side because of the compound curves and not having an English wheel. From the front roll hoop forward and below the center longitudinals are easy. I made all that in one, mostly flat, piece. It's the rest of it, the cockpit top, that's more difficult.

But then again, if you follow the rules and attach the alloy at 6" spacing intervals to bosses welded to the chassis, you will probably stiffen up everything.

[R. Pare]

Kevlar in the body is definetely the easiest, but you really need to increase the number of layers to get the same protection as an alu sheet. You also should do it as a vacuum bagged epoxy resin panel - wet layup with polyester resin will degrade the load dispersion characteristics od kevlar quite a bit.

You can also attach alu or steel panels to the frame as long as no two rivits, bolts, or welds are 6.0" or closer at their centers. If the car is severely underweight, I'd look at welding on steel panels in critical areas - both for penetration protection as well as some stiffening.

[Matt Conrad]

The rules state that you must use one of the following materials between the upper and lower mainframe tubes:

1. .060 Aluminum (6061)
2. 18 Gauge Steel
3. Double Layer of Bi-directional 5 Oz. Kevlar

We will use the aluminum panels, but I do have a roll of 5 oz Kevlar in the storeroom if we decide to go that route.

In addition, Our chassis design provides additional side impact protection by locating several tubes "outboard" from the traditional plane of the side of the car. I can't really find a great picture of it......try this from a while back....




There are a few more tubes that aren't yet attached in this picture, but I hope you get the idea. These tubes are concealed by the sidepods, and in addition to the added side impact protection, contribute to the torsional rigidity of the cockpit section of the chassis.

Matt Conrad
Phoenix Race Cars, Inc.

[Brands]

I really am looking for the light option as I want to get below 1000lbs with me onboard, even if that's only a few lbs under. I am worried about adding Kevlar to the side panels and not causing any distortion in the glass or future delamination. Guess I'll need to experimant a bit.

[Dave Gomberg]

The rules state that you must use one of the following materials between the upper and lower mainframe tubes:

1. .060 Aluminum (6061)
2. 18 Gauge Steel
3. Double Layer of Bi-directional 5 Oz. Kevlar

A small (but important) correction to this: these are minimums - you are free to use thicker aluminum or steel or to use more layers of Kevlar.

Dave

[R. Pare]

Brands:

What car body panels are you speaking of, and what did the car originally have for penetration protection?

ALL FF's & FC's built to the '86 rules were supposed to have one form or another of the minimum required protection - if they didn't, they were illegal!

[Bob Coury]

I have an 88 SE-3. It looks like the kevlar was added as an afterthought. It was only 1 layer. I wanted to add a 2nd layer, and used fiberflass compatable paint stripper to remove the layer of paint that was on the inside. I use a pressure washer to remove all the paint remover, and it started to lift the kevlar. I ended up peeling it all off by hand will start over.

I am also added aluminum panels on the inside of the frame for added protection and for a bead seat support. Because it is a Swift with ducting built into the bodywork I could not install aluminum to the outside of the frame.

[preform resources]

Bob, the problem you had would be typical of softening the resin which allowed you to pull out the reinforcement (kevlar).Kevlar does not absorb the resin as e-glass does your car probably had polyester resin laminated over the kevlar and onto the poly body parts. Ideally you would fab the body from scratch and add the kevlar while the lamination was still wet or tacky the resin then could encapsulate the kevlar and give you a better bond. I would reccomend using epoxy resin for secondary bonding in a prepared surface as epoxy has much better mechanical adhesion than polyester and don't soak the lam with resin .good luck
Dave Craddock

[stephen wilson]

I have an RF78 and have been considering more side impact protection. The aluminum/kevlar gives protection against penetration, but not impact attenuation. Has anyone considered a thicker foam core panel or AL honeycomb for this purpose? I have also considered a paneled thin wall square tube extension outside of the main frame. Any thoughts about effectiveness?
Thanks,
Steve

[RussMcB]

I wanted to bump start this thread and see what people have decided to do recently.

I had been assuming I'd simply form and rivet some aluminum panels in place, but now that I've read the rules more closely, it may not be as simple as I thought. For instance, if I keep my shifter in the same location as before, the aluminum would need to bulge outwards in that area (like the fiberglass body work does to give the right hand more room).

Does they need need to be solid barriers (i.e., no holes) covering the entire area between the upper and lower main frame tubes and front & rear hoop bulkheads? That's a couple of huge areas!

So, now I'm starting to wonder about adding a double layer of Kevlar to the inner sides of the cockpit fiberglass.

Anyone willing to share advice or pictures?

TIA.

[RussMcB]

Brands:

What car body panels are you speaking of, and what did the car originally have for penetration protection?

ALL FF's & FC's built to the '86 rules were supposed to have one form or another of the minimum required protection - if they didn't, they were illegal!

Hey, Richard, what are the chances that my RF94 already has something, such as Kevlar impregnated in my cockpit sides?

[preform resources]

Russ,did you try removig some paint from the body inside,kevlar should still come up yellowish in the laminate.
Dave Craddock

[S Lathrop]

Looking back on this rule and with 20/20 hind sight, we should have specified 8 layers of kevlar in epoxy resin. As a rule of thumb, if you want an equivalent structure in kevlar composite to an aluminum structure then use the same thickness as aluminum in a single laminate ( each layer of kevlar is .008 inch thick). These thickness assume vacume bagged and minimum resin to fully wet the fabric.

What was specisified was the Kevlar equivalenc of .016 aluminum at best.

[R. Pare]

Russ:

I would suspect that just about every car anyone built after the mid '80's was built using kevlar instead of the previously popular aluminium panels.

However, I have also been somewhat suspicious of many English chassis over the years where kevlar was supposedly used, but was not easy to verify ( visible to direct line of sight with the panels still on the car). I've heard some claim that "fine weave black English kevlar" was used, but, frankly I've never heard of the stuff! Doesn't mean that there isn't such an animal, just that it's existance I cannot either prove or disprove - someone else here may have the definitive answer to that!

As for coverage area - I'd have to back to look at the rule wording to see exactly what is stated, but simple logic (to me at least!) would dictate that any place that something can penetrate and hit the driver would need to be covered.

[RussMcB]

Here is how the rule is stated:

The area between the upper and lower mainframe tubes from the front roll hoop bulkhead to the rear roll hoop bulkhead shall incorporate one of the following:
a. Panel(s), minimum of either .060 inch heat-treated aluminum (6061-T6 or equivalent) or eighteen (18) gauge steel, attached outside of the chassis tubes.
b. Reinforced body - at a minimum, consisting of a double layer, five (5) oz., bi-directional, laminated Kevlar material incorporated into the body which shall be securely fastened to the frame.

[RussMcB]

Possible interpretation of the way it is worded:

I could add an aluminum panel that covers, say, 60% of the side. I could argue that the "area incorporates a panel". In other words, it doesn't explicitly say the entire area must be covered.

Just kicking around ideas before I decide how to tackle it.

[R. Pare]

OK. Rules Wording Meanings Lesson #.... "

The rule brings us back to the debate over the floorpan rule we all so enjoyed last fall.

The rule in this case gives a pretty ironclad intication of the expected minimum boundaries;

In the first part of the area boundaries description, the minimum vertical coverage description is : "The area between the upper and lower frame rails......." . Since it has no qualifiers,it is an absolute - ie - it means ALL of the area between those rails, not part of the area, not selected portions of the area.


The second part of the sentance describing the longitudinal boundaries - "from the front roll hoop bulkhead to the rear roll hoop bulkhead" - is also all-inclusive of every inch between those 2 points.

Sorry, but if you want to go the aluminium panel route, I'm afraid that the coverage area required is more inclusive than you'd like to tackle!

Frankly, it would be a LOT less work to vacuum bag in the required kevlar layers if you are unablr to verify that your car already has the kevlar in the factory panels.

[RussMcB]

Frankly, it would be a LOT less work to vacuum bag in the required kevlar layers if you are unablr to verify that your car already has the kevlar in the factory panels.

I'd like to learn more about how to do this. Is it something that can be done in a home garage? Is there someone, perhaps a company, that offers this service (at a reasonable price)? What might be a ballpark cost compared to the aluminum alternative?

I've only done basic fiberglass work. Are there similarities, or are they very different processes?

TIA.

[Brands]

Russ,

I've added two layers of 5oz kevlar to each glass side panel on my car, in the required area. I was a little worried about how to do it so I experimented on some older scrap panels first using the advice of a friend at work who lives and breaths fiberglass!. It really is easy. As long as the area is free from paint, oil and grease and well keyed in (80 grit sanding wheel) it will bond just fine using poly resin. I've bent, twisted, stamped on and even tried to pry off the experimantal part and it won't budge. I have painted the inside of my new side panels but masked off two 'stripes' to show the original kevlar for tech purposes. You can still clearly see the weave through the paint as well. If you look at the last photo of the pedal area in my car you can clearly see the kevlar. I've got some left over so if you fancy a trip north it's yours.

Ben

[RussMcB]

Thanks, Ben. Very generous. I've sent you a PM.

[formulasuper]

Looking back on this rule and with 20/20 hind sight, we should have specified 8 layers of kevlar in epoxy resin. As a rule of thumb, if you want an equivalent structure in kevlar composite to an aluminum structure then use the same thickness as aluminum in a single laminate ( each layer of kevlar is .008 inch thick). These thickness assume vacume bagged and minimum resin to fully wet the fabric.

What was specisified was the Kevlar equivalenc of .016 aluminum at best.

So, according to Steve, & I do trust his info, if you guys use only the two layers specified you will only be meeting the misdirected GCR requirements & only be getting the protection of .016 aluminum instead of .060. Having much experience with sheet aluminum I wouldn't feel very protected with .016, even if it is 6061-T6 or equivalent. If I was going to the trouble I'd use the 8 layers & feel better about it. Of course some of you have been racing for years with neither, so....

[preform resources]

Scott, keep in mind you are sitting in an aluminum double walled tub and the side pods are rather tall compared to a typical Van Dieman giving you a lot of crush area in a side impact.and I'm sure a lot of f-atlantic and super vee guys have experienced the occaisional t-bone.I'm not saying there's no reason for concern but you are less vulnerable than the average tube chassied car .


By the way Steve makes a good point about using epoxy resin ,particularly with kevlar,but good preperation is essential for bonding to the original substrate, IE; totally free of paint and as Ben said roughed up with 80 grit to provide the best adhesion.
Dave Craddock

[formulasuper]

Scott, keep in mind you are sitting in an aluminum double walled tub and the side pods are rather tall compared to a typical Van Dieman giving you a lot of crush area in a side impact.and I'm sure a lot of f-atlantic and super vee guys have experienced the occaisional t-bone.I'm not saying there's no reason for concern but you are less vulnerable than the average tube chassied car .
Dave Craddock

Dave, I'm not considering any extra protection for my Ralt. Like you said, it has double wall aluminum on both sides of the tub, plus aluminum honeycomb crush material in the walls. In addition, there is extra aluminum glassed onto the inside of the outer sidepod walls. I figure with all this the monoque chassis is stronger than a tube frame car & is one of the reasons my car is 180 lbs heavier than the FC based F1000 cars.